The transferring of fibers or other flexible filamentary material from a cocoon, spinneret, extrusioned eye, spinning frame or the like, onto a spool, a reel or a similar holding receptacle in a particular pattern is the basic step in the formation or processing of a yarn.
As hereinafter used and referred to, a single yarn is the simplest strand of material suitable for weaving or knitting, which if untwisted, will separate into the individual fibers from which it was made. Also, the international denier as herein used is defined as a skein of yarn 450 meters long which weighs 0.05 grams. For manmade yarn 20 .times. 450 or 9,000 meters of a 1 denier yarn weighs 1 gram. 9,000 meters of 2 denier yarn weighs 2 grams.
The composition of any yarn must be of a character in accordance with the type or form of fabric into which the yarn is to be woven. A tightly woven fabric, for example, can be made from a single strand of a filament or single ply. In some instances a yarn is desired, wherein in other instances a plied or folded yarn made up of two or more single yarns is required.
In certain other instances commingled yarns comprising 2 or more natural or manmade fibers in varying percentages, are desired to achieve a specific character of the finished textile product. Once the specific fibers are selected the proper yarn denier and texture should be maintained to assure that there will be the desired uniformity of character in the subsequently woven or knitted product.
In any instance, when the desired yarn composition and/or denier is interrupted during a machine processing step, it becomes necessary to stop the equipment, make the necessary corrections, and then proceed with the operation.
In an exemplary situation a spool or package of feeder yarn can be required to hold a continuous, single yarn of a specific denier or weight per unit length. However, during the high speed transfer to a wind-up reel, a second strand from an adjacent location can inadvertently become intermeshed therewith such that both strands are then drawn together onto the wind-up reel. Thereafter, unless immediate detection is made of this malfunction, and corrected, the desired single yarn pattern might continue uncorrected.
Such a defect in the wound yarn spool will become pertinent during a later unreeling for the next processing operation, or for the final knitting or weaving operation. At the latter, the necessary changes and corrections to material and equipment can be both expensive and time consuming.
A further persistent and recurring problem is the breaking of a yarn strand at any point in its processing. A skilled operator in such an instance must detect the yarn break and rapidly splice the broken ends with a minimum amount of loss of time. A weaver's knot or splice when correctly made in the broken segments, can have a diameter up to 6 to 8 times the diameter of the yarn. This knot or splice must of course pass freely through any monitoring device interposed along the path of the moving yarn without breaking the yarn at the splice.
Toward overcoming these persistent and recurring problems, the presently disclosed apparatus and method of use includes means to continuously monitor and detect denier variation in a yarn processing operation to maintain a degree of yarn uniformity and quality. Detection takes the form of an elongated, constricted passage means through which a yarn line passes. Functionally, the apparatus will instantaneously determine when a desired yarn composition or pattern is interrupted by the addition to, loss of, or change in one or more strands. The detection means further triggers the necessary ancillary circuitry to provide a signal to indicate or record the presence or location of the defect, or to stop the operating equipment in a manner that needed corrections can be made. For example, the signal can be utilized to initiate a cutter apparatus to excise the defective yarn, make a splice, and then continue the operation.
The diameter and length of the constricted passage thus constitutes a reaction to a flow of a sensing fluid which is introduced to the passage along with the yarn. To conserve the supply of the regulated sensing fluid, air for example, the sensing unit should offer a high impedance to the fluid flow. An aspect ratio relating to passage length to passage diameter, should be on the order of magnitude of 400 to 1. With a strand of yarn passing through such a constricted passage, impedance rises greatly. A primary purpose of the disclosed apparatus therefore is to detect and indicate a broken end or a strand break. Further, to detect passage of two strands when only one is desired, or detect the absence of a strand when two or more are desired to be in the yarn structure.
By carefully balancing the volume and pressure of the sensing fluid the disclosed apparatus functions with considerable versatility. For example it functions to monitor the homogeneity of twisted, crimped, and commingled textured yarns which are treated to give the yarns resilience, stretchability, bulk, and liveliness. These characteristics of course increase the salability and desirability of yarns to a purchaser.
It should be noted that a yarn which has been crimped, oiled, and textured to cause the fibers to more readily entangle with each other, exhibits an increase in bulk of 200 to 300% over an untextured filament of the same denier. If this bulkiness of textured yarn is uniform such yarn can occupy the entire volume of the elongated sensing passage, its commingled fibers would understandably offer a throttling effect upon the sensing fluid.
If the required tension maintained upon a textured yarn is applied within controlled limits, the hereinafter disclosed apparatus can be arranged to detect an extremely small pneumatic input signal. It will further convert the signal to a fluid flow circuit, and amplify the flow by means of modulation. The resultant output can then be used to control and regulate a pneumatic or electrically controlled device.
To illustrate the invention, the following description of the disclosed apparatus and method therefor are directed to the use of a single yarn as being the desired embodiment. It can be appreciated nonetheless that the disclosed method can be directed as well to the provision of plied yarns, blended or commingled yarns, and yarns having a particularly desired texture. Further, it is within the ambit of the invention that the process can be applied to filamentary products other than yarns for carpets, curtains, and wearing apparel, including certain forms of rope, wire, cable, twine, thread, or similar flexible products adapted to be wound onto a spool or a reel.
An object of the invention therefore is to provide a method and apparatus for continuously monitoring a yarn line for the purpose of detecting a malfunction or defects in the yarn processing operation. A further object is to provide a novel detection system for continuously monitoring a rapidly moving yarn line to assure the maintenance of the uniformity and quality of the product. A still further object is to provide means to instantaneously detect a break in a moving yarn line during a processing step.